1. Field of the Invention
The present invention relates to a method for processing a substrate and methods for producing a liquid ejection head and a substrate for use in a liquid ejection head.
2. Description of the Related Art
An example of a liquid ejection apparatus configured to eject a liquid from an ejection orifice is an ink-jet recording apparatus configured to perform recording by ejecting a liquid ink onto a recording medium. The liquid ejection apparatus includes a liquid ejection head.
The liquid ejection head includes a substrate having a nozzle material layer provided on one surface of the substrate. The nozzle material layer has an ejection orifice and a nozzle configured to eject the liquid. The substrate has a liquid supply port configured to supply the nozzle material layer with the liquid. The substrate is provided with an ejection energy-generating element configured to generate energy used for the ejection of the liquid. The liquid ejection head ejects the liquid using the energy generated by the ejection energy-generating element.
As the liquid ejection head, an ink-jet head (hereinafter, referred to as a “side-shooter head”) configured to eject a liquid in the direction perpendicular to the substrate has been known. The side-shooter head includes a substrate having a through hole serving as a liquid supply port. The liquid ejection head is supplied with a liquid through the liquid supply port. The liquid supply port is formed by a technique for processing a substrate.
U.S. Pat. No. 6,143,190 discloses a method for producing a side-shooter liquid ejection head. To prevent nonuniformity in the diameter of openings, the method for producing a liquid ejection head described in U.S. Pat. No. 6,143,190 includes the steps (A) to (F):                (A) forming a sacrificial layer on a portion of one surface of a substrate where a through hole will be formed, the sacrificial layer being capable of being selectively etched without etching the material of the substrate,        (B) forming an etch stop layer having etching resistance so as to cover the sacrificial layer arranged on the substrate,        (C) forming an etching mask layer on the other surface opposite the one surface of the substrate, the etching mask layer having an opening corresponding to the sacrificial layer,        (D) etching the substrate by crystal orientation-dependent anisotropic etching until the sacrificial layer is exposed through the opening,        (E) removing the sacrificial layer by etching the sacrificial layer from a portion that has been exposed in the step (D), and        (F) partially removing the etch stop layer to form a through hole.        
U.S. patent application serial No. 2007/0212891 discloses that in a method for producing a liquid ejection head, a blind hole is formed with laser light before anisotropic etching is performed.
In the case where a liquid supply port is formed in a substrate by etching as in U.S. Pat. No. 6,143,190, the etching may require a substantial amount of time, which may disadvantageously reduce production efficiency.
In the method for producing a liquid ejection head described in U.S. patent application serial No. 2007/0212891, the blind hole is formed in the other surface opposite one surface of the substrate with laser light before a liquid supply port is formed in the substrate by etching. However, it can be difficult to precisely control the depth of the blind hole with the laser light.
In the case where a hole extending to a portion near the one surface of the substrate is formed, the hole can pass through the substrate. In this case, a nozzle material layer arranged on the one surface of the substrate can be impaired by the laser light. It can thus be difficult to stably form a deep hole in the substrate.